The invention concerns a device for damping the pitching of an engine-driven vehicle with a chassis and axles, of which at least one is fixed rigidly on the chassis, and with flexible tyres.
In connection with vehicles having axles mounted fixedly (unflexibly) on the chassis, like construction machines, forest machines, agricultural machines, skid-steered loaders, caterpillar tractors with pneumatic tyres and similar vehicles, the upper part of the vehicle, when driving, usually performs pitching, that is, oscillating movements, around an axis, which is parallel to the axles. The frequency and the amplitude of the pitching depend on the speed and the load of the vehicle.
The reason for the pitching is that the axles are mounted fixedly on the vehicle chassis, meaning that the only flexibility comes from the pneumatic tyres.
In order to damp the pitching of a vehicle with a working device operated by a hydraulic cylinder, it is known either to insert a cushion for the boom cylinder in the hydraulic system (U.S. Pat. No. 5,195,864) or to control the oil supply to the hydraulic cylinder and thus also the. relative position of the working device (U.S. Pat. No. 5,897,287). In order to dampen the pitching of a tractor, for example when driving in the roads with a mounted plow, it is further known (EP 0 518 226 A1) to provide the front axle with an active damping in the form of a damping cylinder, which counteracts the pitching.
Influencing the steering of the working device in order to remedy pitching would also influence the desired movement of the working device during operation. The insertion of an additional damping cylinder is expensive.
It is therefore a principal object of this invention to provide a device for damping the pitching of an engine driven vehicle, which does not require influences on the steering of a possible working device, and which has a simple design.
A further object of the invention is to influence the torque on at least one of the wheels supported on the axles, is influence by a measure of the pitching of the vehicle in such a way that the pitching is dampened.
These and other objects will be apparent to those skilled in the art.
A device for damping the pitching of an engine-driven vehicle with a chassis and axles, of which.at least one axle is mounted fixedly on the chassis, and with flexible tires, characterised in that the torque of at least one of the wheels (4) supported on the axles (5) is influenced in dependence of a measure of the pitching of the vehicle (21) in such a way that the pitching is damped.